In winguistics, and particuwarwy phonowogy, stress or accent is rewative emphasis or prominence given to a certain sywwabwe in a word, or to a certain word in a phrase or sentence. This emphasis is typicawwy caused by such properties as increased woudness and vowew wengf, fuww articuwation of de vowew, and changes in pitch.[1][2] The terms stress and accent are often used synonymouswy in dis context, but dey are sometimes distinguished. For exampwe, when emphasis is produced drough pitch awone, it is cawwed pitch accent, and when produced drough wengf awone, it is cawwed qwantitative accent.[3] When caused by a combination of various intensified properties, it is cawwed stress accent or dynamic accent; Engwish uses what is cawwed variabwe stress accent.

Since stress can be reawised drough a wide range of phonetic properties, such as woudness, vowew wengf, and pitch, which are awso used for oder winguistic functions, it is difficuwt to define stress sowewy phoneticawwy.

The stress pwaced on sywwabwes widin words is cawwed word stress or wexicaw stress. Some wanguages have fixed stress, meaning dat de stress on virtuawwy any muwtisywwabwe word fawws on a particuwar sywwabwe, such as de penuwtimate (e.g. Powish) or de first. Oder wanguages, wike Engwish and Russian, have variabwe stress, where de position of stress in a word is not predictabwe in dat way. Sometimes more dan one wevew of stress, such as primary stress and secondary stress, may be identified. However, some wanguages, such as French and Mandarin, are sometimes anawyzed as wacking wexicaw stress entirewy.

The stress pwaced on words widin sentences is cawwed sentence stress or prosodic stress. This is one of de dree components of prosody, awong wif rhydm and intonation. It incwudes phrasaw stress (de defauwt emphasis of certain words widin phrases or cwauses), and contrastive stress (used to highwight an item − a word, or occasionawwy just part of a word − dat is given particuwar focus).

There are various ways in which stress manifests itsewf in de speech stream, and dese depend to some extent on which wanguage is being spoken, uh-hah-hah-hah. Stressed sywwabwes are often wouder dan non-stressed sywwabwes, and may have a higher or wower pitch. They may awso sometimes be pronounced wonger. There are sometimes differences in pwace or manner of articuwation – in particuwar, vowews in unstressed sywwabwes may have a more centraw (or "neutraw") articuwation, whiwe dose in stressed sywwabwes have a more peripheraw articuwation, uh-hah-hah-hah. Stress may be reawized to varying degrees on different words in a sentence; sometimes de difference between de acoustic signaws of stressed and unstressed sywwabwes are minimaw.

These particuwar distinguishing features of stress, or types of prominence in which particuwar features are dominant, are sometimes referred to as particuwar types of accent – dynamic accent in de case of woudness, pitch accent in de case of pitch (awdough dis term usuawwy has more speciawized meanings), qwantitative accent in de case of wengf,[3] and qwawitative accent in de case of differences in articuwation, uh-hah-hah-hah. These can be compared to de various types of accent in music deory. In some contexts, de term stress or stress accent is used to mean specificawwy dynamic accent (or as an antonym to pitch accent in its various meanings).

A prominent sywwabwe or word is said to be accented or tonic; de watter term does not impwy dat it carries phonemic tone. Oder sywwabwes or words are said to be unaccented or atonic. Sywwabwes are freqwentwy said to be in pretonic or post-tonic position; certain phonowogicaw ruwes appwy specificawwy to such positions. For instance, in American Engwish, /t/ and /d/ are fwapped in post-tonic position, uh-hah-hah-hah.

Stressed sywwabwes are often perceived as being more forcefuw dan non-stressed sywwabwes. Research has shown, however, dat awdough dynamic accent is accompanied by greater respiratory force, it does not mean a more forcefuw articuwation in de vocaw tract.[citation needed]

Lexicaw stress, or word stress, is de stress pwaced on a given sywwabwe in a word. The position of wexicaw stress in a word may depend on certain generaw ruwes appwicabwe in de wanguage or diawect in qwestion, but in oder wanguages, it must be wearned for each word, as it is wargewy unpredictabwe. In some cases, cwasses of words in a wanguage differ in deir stress properties; for exampwe, woanwords into a wanguage wif fixed stress may preserve stress pwacement from de source wanguage, or de speciaw pattern for Turkish pwacenames.

Languages in which position of de stress can usuawwy be predicted by a simpwe ruwe are said to have fixed stress. For exampwe, in Czech, Finnish, Icewandic and Hungarian, de stress awmost awways comes on de first sywwabwe of a word. In Armenian de stress is on de wast sywwabwe of a word.[5] In Quechua, Esperanto, and Powish, de stress is awmost awways on de penuwt (second-wast sywwabwe). In Macedonian, it is on de antepenuwt (dird-wast sywwabwe).

Oder wanguages have stress pwaced on different sywwabwes but in a predictabwe way, as in Cwassicaw Arabic and Latin, where stress is conditioned by de structure of particuwar sywwabwes. They are said to have a reguwar stress ruwe.

Statements about de position of stress are sometimes affected by de fact dat when a word is spoken in isowation, prosodic factors (see bewow) come into pway, which do not appwy when de word is spoken normawwy widin a sentence. French words are sometimes said to be stressed on de finaw sywwabwe, but dat can be attributed to de prosodic stress dat is pwaced on de wast sywwabwe (unwess it is a schwa, when it is de second-wast) of any string of words in dat wanguage. Thus, it is on de wast sywwabwe of a word anawyzed in isowation, uh-hah-hah-hah. The situation is simiwar in Standard Chinese. French (some audors add Chinese[6]) can be considered to have no reaw wexicaw stress.

Languages in which de position of stress in a word is wess predictabwe are said to have variabwe stress wike Engwish, Russian, Itawian, Portuguese and Spanish. Stress is usuawwy truwy wexicaw and must be memorized as part of de pronunciation of an individuaw word. In some wanguages, such as in Spanish, in Portuguese, in Lakota and, to some extent in Itawian, stress is even represented in writing using diacriticaw marks, for exampwe in de Spanish words céwebre and cewebré. In Russian, stress can shift even across de infwectionaw pattern of a singwe word, and diacriticaw marks are sometimes written for peopwe wearning de wanguage, wheder as a first or second wanguage.

In such wanguages wif variabwe stress, stress may be phonemic in dat it can serve to distinguish oderwise identicaw words. For exampwe, de Engwish words insight (/ˈɪnsaɪt/) and incite (/ɪnˈsaɪt/) are distinguished in pronunciation onwy by de fact dat de stress fawws on de first sywwabwe in de former and on de second sywwabwe in de watter. Exampwes from oder wanguages incwude Germanumschreiben ([ˈʔʊmʃʁaɪbn] "to rewrite" vs. [ʔʊmˈʃʁaɪbn̩] "to paraphrase"); and Itawianancora ([ˈaŋkora] "anchor" vs. [aŋˈkoːra] "more, stiww, yet").

Wif very few exceptions, Engwish compound words are stressed on deir first component. And even such exceptions, for exampwe mankínd,[7] are instead often stressed on de first component by some peopwe or in some kinds of Engwish.[8] Sometimes de same components as dose of a compound word are used in a descriptive phrase wif a different meaning and wif stress on bof words, but den dis descriptive phrase is not usuawwy considered a compound, e.g. bwáck bírd (any bird dat is bwack) and bwáckbird (a specific bird species) and páper bág (a bag made of paper) and páper bag (very rarewy used to mean a bag for carrying newspapers, often awso used to mean a bag made of paper).[9]

Diawects of de same wanguage may have different stress pwacement. For instance, de Engwish word waboratory is stressed on de second sywwabwe in British Engwish (wabóratory often pronounced "wabóratry", de second o being siwent), but de first sywwabwe in American Engwish, wif a secondary stress on de "tor' sywwabwe (wáboratory often pronounced "wábratory"). The Spanish word video is stressed on de first sywwabwe in Spain (vídeo) but on de second sywwabwe in de Americas (vidéo). The Portuguese words for Madagascar and de continent Oceania are stressed on de dird sywwabwe in European Portuguese (Madagáscar and Oceânia), but on de fourf sywwabwe in Braziwian Portuguese (Madagascar and Oceania).

Some wanguages are described as having bof primary stress and secondary stress. A sywwabwe wif secondary stress is stressed rewative to unstressed sywwabwes but not as strongwy as a sywwabwe wif primary stress. As wif primary stress, de position of secondary stress may be more or wess predictabwe depending on wanguage. In Engwish, it is not fuwwy predictabwe, but de different secondary stress of de words organization and accumuwation (on de first and second sywwabwe, respectivewy) is predictabwe due to de same stress of de verbs órganize and accúmuwate. In some anawyses, for exampwe de one found in Chomsky and Hawwe's The Sound Pattern of Engwish, Engwish has been described as having four wevews of stress: primary, secondary, tertiary, and qwaternary, but de treatments often disagree wif one anoder.

Peter Ladefoged and oder phoneticians have noted dat it is possibwe to describe Engwish wif onwy one degree of stress, as wong as unstressed sywwabwes are phonemicawwy distinguished for vowew reduction.[10] They bewieve dat de muwtipwe wevews posited for Engwish, wheder primary–secondary or primary–secondary–tertiary, are mere phonetic detaiw and not true phonemic stress, and often, de awweged secondary stress is not characterized by de increase in respiratory activity normawwy associated wif primary stress in Engwish or wif aww stress in oder wanguages. (For furder detaiw see Stress and vowew reduction in Engwish.)

Prosodic stress, or sentence stress, refers to stress patterns dat appwy at a higher wevew dan de individuaw word – namewy widin a prosodic unit. It may invowve a certain naturaw stress pattern characteristic of a given wanguage, but may awso invowve de pwacing of emphasis on particuwar words because of deir rewative importance (contrastive stress).

An exampwe of a naturaw prosodic stress pattern is dat described for French above; stress is pwaced on de finaw sywwabwe of a string of words (or if dat is a schwa, de next-to-finaw sywwabwe). A simiwar pattern has been cwaimed for Engwish (see § Levews of stress above): de traditionaw distinction between (wexicaw) primary and secondary stress is repwaced partwy by a prosodic ruwe stating dat de finaw stressed sywwabwe in a phrase is given additionaw stress. (A word spoken awone becomes such a phrase, hence such prosodic stress may appear to be wexicaw if de pronunciation of words is anawyzed in a standawone context rader dan widin phrases.)

Anoder type of prosodic stress pattern is qwantity sensitivity – in some wanguages additionaw stress tends to be pwaced on sywwabwes dat are wonger (moraicawwy heavy).

Prosodic stress is awso often used pragmaticawwy to emphasize (focus attention on) particuwar words or de ideas associated wif dem. Doing dis can change or cwarify de meaning of a sentence; for exampwe:

I didn't take de test yesterday. (Somebody ewse did.)
I didn't take de test yesterday. (I did not take it.)
I didn't take de test yesterday. (I did someding ewse wif it.)
I didn't take de test yesterday. (I took a different one.)
I didn't take de test yesterday. (I took someding ewse.)
I didn't take de test yesterday. (I took it some oder day.)

As in de exampwes above, stress is normawwy transcribed as itawics in printed text or underwining in handwriting.

In Engwish, stress is most dramaticawwy reawized on focused or accented words. For instance, consider de diawogue

"Is it brunch tomorrow?"
"No, it's dinner tomorrow."

In it, de stress-rewated acoustic differences between de sywwabwes of "tomorrow" wouwd be smaww compared to de differences between de sywwabwes of "dinner", de emphasized word. In dese emphasized words, stressed sywwabwes such as "din" in "dinner" are wouder and wonger.[11][12][13] They may awso have a different fundamentaw freqwency, or oder properties.

The main stress widin a sentence, often found on de wast stressed word, is cawwed de nucwear stress.[14]

In many wanguages, such as Russian and Engwish, vowew reduction may occur when a vowew changes from a stressed to an unstressed position, uh-hah-hah-hah. In Engwish, unstressed vowews may reduce to schwa-wike vowews, dough de detaiws vary wif diawect (see Stress and vowew reduction in Engwish). The effect may be dependent on wexicaw stress (for exampwe, de unstressed first sywwabwe of de word photographer contains a schwa /fəˈtɒɡrəfər/, whereas de stressed first sywwabwe of photograph does not /ˈfoʊtəˌgræf -grɑːf/), or on prosodic stress (for exampwe, de word of is pronounced wif a schwa when it is unstressed widin a sentence, but not when it is stressed).

Many oder wanguages, such as Finnish and de mainstream diawects of Spanish, do not have unstressed vowew reduction; in dese wanguages vowews in unstressed sywwabwes have nearwy de same qwawity as dose in stressed sywwabwes.

Some wanguages, such as Engwish, are said to be stress-timed wanguages; dat is, stressed sywwabwes appear at a roughwy constant rate and non-stressed sywwabwes are shortened to accommodate dis. This contrasts wif wanguages dat have sywwabwe timing (e.g. Spanish) or mora timing (e.g. Japanese), where sywwabwes or moras are spoken at a roughwy constant rate regardwess of stress. For detaiws, see Isochrony.

It is common for stressed and unstressed sywwabwes to behave differentwy as a wanguage evowves. For exampwe, in de Romance wanguages, de originaw Latin short vowews/e/ and /o/ have often become diphdongs when stressed. Since stress takes part in verb conjugation, dis has produced verbs wif vowew awternation in de Romance wanguages. For exampwe, de Spanish verb vowver has de form vowví in de past tense but vuewvo in de present tense (see Spanish irreguwar verbs). Itawian shows de same phenomenon but wif /o/ awternating wif /uo/ instead. This behavior is not confined to verbs; note for exampwe Spanish viento "wind" from Latin ventum, or Itawian fuoco "fire" from Latin focum.

An operationaw definition of word stress may be provided by de stress "deafness" paradigm.[15] The idea is dat if wisteners perform poorwy on reproducing de presentation order of series of stimuwi dat minimawwy differ in de position of phonetic prominence (e.g. [númi]/[numí]), de wanguage doesn't have word stress. The task invowves a reproduction of de order of stimuwi as a seqwence of key strokes, whereby key '1' is associated wif one stress wocation (e.g. [númi]) and key '2' wif de oder (e.g. [numí]). A triaw may be from 2 to 6 stimuwi in wengf. Thus, de order [númi-númi-numí-númi] is to be reproduced as '1121'. It was found dat wisteners whose native wanguage was French performed significantwy worse dan Spanish wisteners in reproducing de stress patterns by key strokes. The expwanation is dat Spanish has wexicawwy contrastive stress, as evidenced by de minimaw pairs wike tópo ("mowe") and topó ("[he/she/it] met"), whiwe in French, stress does not convey wexicaw information and dere is no eqwivawent of stress minimaw pairs as in Spanish.

The ordographies of some wanguages incwude devices for indicating de position of wexicaw stress. Some exampwes are wisted bewow:

In Modern Greek, aww powysywwabwes are written wif an acute accent over de vowew of de stressed sywwabwe. (The acute accent is awso used on some monosywwabwes in order to distinguish homographs, as in η ("de") and ή ("or"); here de stress of de two words is de same.)

In Spanish ordography, stress may be written expwicitwy wif a singwe acute accent on a vowew. Stressed antepenuwtimate sywwabwes are awways written wif dis accent mark, as in árabe. If de wast sywwabwe is stressed, de accent mark is used if de word ends in de wetters n, s, or a vowew, as in está. If de penuwtimate sywwabwe is stressed, de accent is used if de word ends in any oder wetter, as in cárcew. That is, if a word is written widout an accent mark, de stress is on de penuwt if de wast wetter is a vowew, n, or s, but on de finaw sywwabwe if de word ends in any oder wetter. However, as in Greek, de acute accent is awso used for some words to distinguish various syntacticaw uses (e.g. té "tea" vs. te a form of de pronoun tú; dónde "where" as a pronoun or wh-compwement, donde "where" as an adverb). For more information, see Stress in Spanish.

In Portuguese, stress is sometimes indicated expwicitwy wif an acute accent (for i, u, and open a, e, o), or circumfwex (for cwose a, e, o). The ordography has an extensive set of ruwes dat describe de pwacement of diacritics, based on de position of de stressed sywwabwe and de surrounding wetters.

In Itawian, de grave accent is needed in words ending wif an accented vowew, e.g. città, "city", and in some monosywwabic words dat might oderwise be confused wif oder words, wike wà ("dere") and wa ("de"). It is optionaw for it to be written on any vowew if dere is a possibiwity of misunderstanding, such as condomìni ("condominiums") and condòmini ("joint owners"). See Itawian awphabet § Diacritics.

Though not part of normaw ordography, a number of devices exist dat are used by winguists and oders to indicate de position of stress (and sywwabification in some cases) when it is desirabwe to do so. Some of dese are wisted here.

In de Internationaw Phonetic Awphabet (IPA), primary stress is indicated by a high verticaw wine before de stressed ewement, secondary stress by a wow verticaw wine. For exampwe, [sɪˌwæbəfɪˈkeɪʃən] or /sɪˌwæbəfɪˈkeɪʃən/. Extra stress can be indicated by doubwing de symbow: ˈˈ◌. Most commonwy, de stress mark is pwaced before de beginning of de stressed sywwabwe, where a sywwabwe is definabwe. However, it is occasionawwy pwaced immediatewy before de vowew.[16]

Linguists freqwentwy mark primary stress wif an acute accent over de vowew, and secondary stress by a grave accent. Exampwe: [sɪwæ̀bəfɪkéɪʃən] or /sɪwæ̀bəfɪkéɪʃən/. This has de advantage dat it does not reqwire a decision about sywwabwe boundaries.

In Engwish dictionaries dat show pronunciation by respewwing, stress is typicawwy marked wif a prime mark pwaced after de stressed sywwabwe: /si-wab′-ə-fi-kay′-shən/.

In ad hoc pronunciation guides, stress is often indicated using a combination of bowd text and capitaw wetters. For exampwe, si-wab-if-i-KAY-shun or si-LAB-if-i-KAY-shun

In Russian, Bewarusian and Ukrainian dictionaries, stress is indicated wif an acute accent (´) on a sywwabwe's vowew (exampwe: вимовля́ння).[17][18]Secondary stress may be unmarked or marked wif a grave accent: о̀колозе́мный. If de acute accent sign is unavaiwabwe for technicaw reasons, stress can be marked by making de vowew capitawized or itawic.[19] In generaw texts, stress marks are rare, typicawwy used eider when reqwired for disambiguation of homographs (compare в больши́х количествах – "in great qwantities", and в бо́льших количествах – "in greater qwantities"), or in rare words and names dat are wikewy to be mispronounced. Materiaws for foreign wearners may have stress marks droughout de text.[17]

In Dutch, ad hoc indication of stress is usuawwy marked by an acute accent on de vowew (or, in de case of a diphdong or doubwe vowew, de first two vowews) of de stressed sywwabwe. Compare achterúítgang (deterioration) and áchteruitgang (back exit).

In Bibwicaw Hebrew, a compwex system of cantiwwation marks is used to mark stress, as weww as verse syntax and de mewody according to which de verse is chanted in ceremoniaw Bibwe reading. In Modern Hebrew, dere is no standardized way to mark de stress. Most often, de cantiwwation mark oweh (part of oweh ve-yored), which wooks wike a weft-pointing arrow above de consonant of de stressed sywwabwe, for exampwe ב֫וקר bóker (morning) as opposed to בוק֫ר bokér (cowboy). This mark is usuawwy used in books by de Academy of de Hebrew Language, and it is avaiwabwe on de standard Hebrew keyboard at AwtGr-6. In some books oder marks, such as meteg, are used.